The invention relates to a hand-held power tool comprising a drive motor for driving a tool and a generator, wherein the power tool has at least one heating device with at least one heating element and wherein the generator provides the power for operating the heating device. The invention further relates to a method for operating a heating device of a hand-held power tool of the aforementioned kind.
U.S. Pat. No. 6,232,672 B1 discloses a hand-held power tool whose drive motor drives a generator. The generator provides the power for operating a heating device.
The power generated by the generator varies as a function of the engine speed. At low engine speed only minimal power is available; at high engine speed a lot of power is available. The heating element must be designed such that at low engine speed a sufficient heating action is provided so that, for example, in the case of a carburetor heater, freezing of ambient moisture at the carburetor is prevented. At high engine speed, it must be ensured that no overheating occurs because, in the case of a carburetor heater, overheating causes the generation of vapor bubbles leading to an instable operation of the internal combustion engine.
For controlling the temperature, in known heating devices temperature switches, for example, bimetallic switches, are used. In order to measure the heat in the part to be heated, the temperature switch must have a certain spacing from the heating element itself. In this way, the temperature switch responds sluggishly. In operation of the heating element at very high power, for example, at full load of the drive motor, as a result of the sluggish response of the temperature measurement no satisfactory temperature control can be achieved. In the case of a carburetor heater, disruptions can occur before the temperature switch responds when the heating element is operated at very high power.